Aluminum oxide coatings on Co-rich cathodes and interactions with organic electrolyte

Abstract

Lithium-ion batteries (LIBs) have become essential in modern energy storage; however, their performance is often limited by the stability and efficiency of their components, particularly the cathode and electrolyte. Transition metal layered oxide cathodes, a popular choice for lithium-ion batteries (LIBs), suffer from several degradation mechanisms, including capacity fading, reactions with the electrolyte, unstable cathode-electrolyte interfaces, and lattice breakdown during cycling. In recent years, oxide coating, such as alumina, has emerged as a promising strategy to enhance the durability of cathodes by forming a protective layer that mitigates detrimental reactions and improves the stability of the cathode electrolyte interphase (CEI). This study employs ab initio molecular dynamics (AIMD) simulations to investigate the chemical and mechanical behavior of LiCoO2 cathodes with and without aluminum oxide coatings in contact with an organic electrolyte. We examine the interactions between electrolyte molecules with both bare and coated cathode surfaces, focusing on the decomposition of ethylene carbonate (EC) and dimethyl carbonate (DMC), the formation of oxygen species, and solvation dynamics, and evaluate the mechanical robustness of the cathode-coating interface using calculations of axial strain and cleavage energy. Our findings reveal that alumina coatings effectively reduce electrolyte degradation and stabilize the cathode structure, particularly under high-charge states. The coating's thickness and structural orientation are crucial in enhancing mechanical strength and minimizing detrimental reactions at the cathode-electrolyte interface. These insights contribute to the development of more durable LIBs by optimizing the interface chemistry and mechanical properties, providing a pathway toward higher energy densities and longer cycle life.